Isomerizing hydrocarbons with a halogen-containing catalyst

ABSTRACT

Process for isomerizing a saturated hydrocarbon which is carried out in the presence of a catalyst obtained by contacting a catalyst carrier with a group VIII noble metal compound and with a hydrocarbylaluminium halide.

United States Patent Franck et al.

Sept. 2, 1975 ISOMERIZING HYDROCARBONS WITH A HALOGEN-CONTAINING CATALYST Inventor's: Jean-Pierre Franck, Bougival;

Germain Martino, Poissy; Bernard Torck, Boulogtie-sur-S'eine. all of France Assignee: lnstitut Francaise du Petrole. des

Carburants et Lubrifiants, Rueil-Malmaison, France Filed: Nov. 7, 1973 Appl. No.: 413,636

Foreign Application Priority Data Nov. 10, 1972 France 72.39972 US. Cl. 260/683.68; 252/430; 260/666 P Int. Cl. C070 5/30 Field of Search 26()/683.-65, 683.68, 666 P; 252/430 Primary Iirumt'ner'Paul M. Coughlan, Jr. Attorney, Agent. or FirmMil1en, Raptes & White [57} ABSTRACT Process for isomerizing a saturated hydrocarbon which is carried out in the presence of a catalyst oh tuined by contacting a catalyst carrier with a group V111 noble metal compound and with a hydrocarbylaluminium halide.

14 Claims, N0 Drawings ISOMERIZING HYDRocARBoNs WITH A HALOGEN-CON'IAIMNG CATALYST This invention concerns a process fiirisomerizi'ng hydrocarbons with a catalyst containing a'noble metal from group VIII of the periodic Classification of elements. Supported on an inorganic or organic solid carrier. i i

It is already known that the isomerization of straight chain saturated hydrocarbons becomes more efficient the temperature is decreased but that only a few catalysts have a sufficient activity for being used in this operation.

According to a known technique. isonierization cata lysts are prepared by incorporating aluminum trichloride in platinum/alumina catalysts. This can be achieved by sublimating aluminum t richloride or by incorporating an alkyl-aluminum compound and subsequcntly converting the same to aluminum trichloride by means of a hiliOgCl'lLltilig agent. for example H Cl.

This invention is based on a different concept since it makes use directly. as the isomerization catalyst. of the reaction product of a hydrocarbylaluminum halide with a carrier such as alumina and a noble metal compound.

' The catalysts used in the process of this invention are obtained by contacting a catalyst carrier with a compound of a noble metal from group Vlll of the classification and with a hydrocarbylaluminum halide.

The latter has preferably the general formula Al X R in which may be I or 2. X is a halogen. preferably chlorine and R is a hydrocarbon monovalent radical, for example a saturated. linear or branched alkyl radical which may contain from 1- to 20 carbon atoms.

'The step of contacting the carrier with the compound of a metal from group Vlll may be achieved before. z ift er or simultaneously with the step of contacting the carrier with the aluminum compound.

As examples of R radicals, there are: methyl. ethyl. normal propyl. normal butyl, iso butyl. phenyl, benzyl and cyclohexyl.

We can make use. for example, of the following hydrocarbylaluminium halides: diethylaluminium chloride.dodecylaluminium dichloride, disobutylaluminum chloride, diphenylalurninum fluoride. benzylaluminum dichloride. cyclohexylaluminum dichloride. hexylaluminum difluoride.

The hydrocarbylaluminum halide may be a single. well defined compound or a mixture, either stoichiometrical or not of various compounds; we can use. for example. a sesquichloridc. such as cthylaluminum sesquichloride of the formula Al Cl,-;(C H

It is necessary for the catalyst to contain one or more metals or compounds of metals having a hydrogenating action, pertaining to group VIII of the periodic classification. The preferred metal is a metal from the platinum family. for example Ru. Rh. Pd. Os. Ir and/or Pt. lts metal content may be from 0.05 to 27( by weight and preferably. from 0.1 to 171 by weight. The metals from the platinum group which are the most particularly suitable are platinum and palladium. The catalyst may also contain associations of catalytic metals. the additional metals pertaining. for example. to other groups than group Vlll. Among said associations. we can mention platinum-iridium. platinum-ruthenium. platinum-tungsten. platinum-rnangancse. platinumrhenium. platinumpalladiurn. platinu rn-iridium-thal- 2 lium or platinum-iridium-manganese. The hydrogenating metal or metal compound may be introduced into the catalyst by any known method. For example. we may precipitate the platinum group metal in the form of a sulfide. or impregnate the carrier by means of chloroplatinic acid or any equivalent acid of another metal.

The preferred carriers are the oxides of metals from groups ll. lll and/or [V of the periodic classification of elements. such for example as the oxides of magne sium. aluminum. titanium. zirconium, thorium or silicium. used either separately or as a mixture or with oxides of other elements of the periodic classification such for example as boron and/or antimony. There can also be used carbon or the protonic form ofa molecular sieve.

The preferred carrier consists essentially of alumina. The most suitable aluminas for the preparation of these catalysts are porous aluminas of high specific surface containing hydrogen which is generally assumed to be in the form of hydroxyl groups. For example. excellent results may be obtained by aluminas prepared by calcination of a B-alumina trihydratc such as bayerite or a mixture of this type of alumina with other caleinated alumina hydrates; however. aluminas prepared by cal cinating other alumina hydrates such as a-alumina trihydrates or gibbsites. u-alurnina mono hydrates or alumina obtained by hydrolysis of aluminum alcoholate may also be convenient. These aluminas are generally remarkable by their very high specific surface. in most cases from 180 to 500 m /g or even more. The most active catalysts are generally obtained when this specific surface is higher than 200 m /g and more particularly higher than 300 m /g.

Before introducing the hydrocarbylaluminum halide. it is essential to subject the substance to be halogenated to a treatment for removing the greatest amount of water and oxygen adsorbed on. the catalyst carrier; at calcination may be suitable. provided it is carried out at such a temperature that the so-called constitutive-OH groups are not removed during this treatment. For example. with an alumina having a specific surface equal to or higher than 5 m /g. the calcination may be conducted between 200 and; 600C and preferably between 300 and 500C. in some cases. it may be advantageous to carry out. after the calcination step, a treatment with hydrogen at a temperature from 200 to 600C and preferably from 300 to 500C in order to reduce the noble metal deposited on or incorporated in the considered oxide.

The hydrocarbylaluminum halide is generally used in solution in a liquid saturated or unsaturated. linear or branched hydrocarbon containing for example from 5 to 20 carbon atoms or in another inert solvent. in particular a halogenated hydrocarbon. We can use advantageously pentanes. hexancs or hcptancs. The halide may be used at a concentration up to the limit of solubility in the considered solvent.

It seems. as a general rule. that a true reaction occurs between the halide and the carrier. for example alumina. This reaction being in most cases quantitative. nearly all the halide contained in the solution. in the form of Al X,,R will be present in the catalyst. It is therefore unnecessary. in most cases. to make use of an excess of this agent.

The halide content may reach several tens "/1 by weight with respect to the solid material and. accord ingly. there will be generally a very large excess of hydrocarbylaluminum halide with respect to the noble 3 metal contained in the carrier. It appears therefore quite surprising that. by such a technique. there can be obtained catalysts which are active for hydroisomerization since it is known. on the contrary. that catalysts of platinum on alumina. when treated by an excess of triethylaluminum.become active in hydrogenation only after a subsequent treatment with hydrogen at 650C and that. in this case. the activity of these catalysts is lower than that of the catalysts which have not been treated with triethylaluminum and have been merely reduced by hydrogen at 427C. g

The reaction between the carrier and the hydrocarbylaluminum halide is preferably conducted in an at- I mospherc free from oxygen and/or oxygenated compounds; in fact. the halogenation agents such. for example. as hydrocarbylaluminumchlorides Al Cl .,R;. are pyrophoric; however it must be emphasized that the halogenated catalysts obtained according to the process of the invention are not pyrophoric. Moreover. it is advantageous to conduct the reaction in an atmosphere free from sulfur and/or nitrogen compounds. Thus. it is possible to efficiently carry out the reaction in an atmosphere of rare gas. hydrogen. nitrogen or gaseous hydrocarbon. these various compounds being taken alone or as mixtures and preliminarily made free from the above-mentioned compounds.

The reaction which consists of contacting the hydrocarbylaluminum halide or its solution with the substance to behalogenated. may be carried out under atmospheric pressure or any other pressure. in an atmosphere such as hereinabove described. in the gaseous or liquid phase at a temperature generally from to 250C. but which may be ashigh 300C. in a static or dynamic manner. No subsequent heating is necessary and the later is even. as a rule. preferably avoided.

It is remarkable that said halogenation technique may be used at temperatures higher than 180C. particularly from 180 to 300C. It is therefore apparent that this technique is substantially different from the techniques consisting of introducing the aluminum trichloride into the platinum alumina catalyst. As a matter of fact. at those high temperatures. aluminum trichloride would sublimate and would not remain on the catalyst:

1n the case of a static operation. said operation. which involves impregnation of a carrier. may be conducted either under dry or wet conditions.

In the case of a dynamic operation. the solution of the halogenating agent may be circulated over the substance to be halogenated. which is arranged in a fixed bed. at a hourly rate of. for example. from 1 to 100 liters of solution per kilogram of catalyst to be halogenated.

The last technique is generally preferred. since:

it makes it possible to halogenate the catalyst'carrier within the reactor itself:

it makes it possible to use the minimum amount of solvent which is compatible with the solubility. irrespective of the halogen amount to be introduced into the catalyst. by a continuous recycling of the solution;

it makes it possible to make use. as solvent for the balogenating agent. of the hydrocarbon feedstockwhich must be converted by means of the catalyst. without substantial loss of the starting material. g

Thus. in the case of a chlorination. it is possible to incorporate to the catalyst. from 1 to by weight of chlorine. preferably from 4 to'l 2% according to the na;- ture and the surface of the carrier. When using another 4 halide than a; chloride. the amount of incorporated halidc is substantially of the same magnitude.

It is also possible to incorporate a portion of the halogen by means QfIhQ'pI'CSCnt method and another portion by rneans of another already known method.

A particularly interesting application of the process of the invention consists inth'e preparation of catalysts active for hydroiso merization at low temperature of paraffins containing for example. from 4 .to 7 carbon mentioned treatment. in anamount of from 0.05 to 2% v by weight. into the catalyst. This treatment is advantageously followed with heating in hydrogenatmosphere at a temperature of from to 600C. so as to reduce the platinum compoundto platinum metal. A catalyst of this type maybe obtained by treating according to the process of the invention. a conventional catalyst of platinum on alumina. The resulting catalyst may subsequently be used in isomerization. under hydrogen atmosphere. of saturated hydrocarbons containing from 4 to 7 carbon atoms and preferably. 5 and/or 6 carbon atoms. ata temperature of from 50 to 250C. for example 100 to 200C. and preferably 100 to C. The operation is preferably conducted under a pressure of from 5 to 100 kg/crn at aspatial velocity of 0.2 to 10 liters of feedstock per liter of catalyst and per hour. The molar ratio H /hydrocarbon is. for example. from 0.01 l to 20: l. and preferably from 1.5 l to 10: 1.

By way of example. as starting material which can be isomerized according to the process of the invention. there may be mentionedthe following hydrocarbons: n-butane. n-pentane. n-hexanc. methylpenta'ne. methylcyclopentane. cyclohexanc. heptane or mixtures thereof.

We 'may'introduce. either continuously or intermittently. in the charge. a halogenated promoter selected from the free halogens. the halohyclric acids and the hydroearbyl halides. for example. hydrochloric acid, chlorine. hydrofluoric acid or an alkyl halide such. for example. as ethyl chloride. isopropyl chloride. tertiobutyl chloride. chloroform. dichloromethane. methyl chloride. trichlorethylene or tertiobutyl bromide. in a proportion of for example. from 10 to 10.000 ppm by weight with respect to thehydrocarbon feedstock. Still higher proportions may be used' but they do not result in any substantial advantage. The alkyl halides contain. for example. from 1 to 6 carbon atoms per molecule.

lt has been observed that the totality or at least a large portion of the halide introduced in the form of a halogenated promoter co'uld be found again in" the 'reactor outflow. either as such or in the form of halohydric acid. Thc promoter or products derived therefrom can thereforebe' iec'oyered at the outlet of the reaction zone and recycledto the inlet thereof. lt suffices to add some fresh promoter. either periodically or in a continuous manner". in. a small proportion of. for example. from 10' to 100 ppm by weight with respect to the hydrocarbon charge. in order'tocompensate the losses.

The following examplesare given for illustrating the invention without. howeyer. limiting the'scope thereof.

EXAMPLE l lmpregnation technique No. l (statie)' [n a reactor of stainless steel. of the (irignard type.

6 %by weight of noble metals from group VIII. The solid material. after calcination. has been subjected to a treatment at 400C in hydrogen. under atmospheric pressure. during 2 hours. in order to reduce the metal a I v t t. equipped with a device for lnJCCtlllg a liquid compound 1mm t? n Mm f dummum under pressure and under controlled atmosphere. we l A u tff q g. czyrrie d out at a introduce 100 g of a reforming catalyst having a 0.35 2 i g g i? the cmby weight content of platinum deposited on an alumina f 3 or O "dung having a specific surface of 416 m /g and a total pore Amount Analysis of Hal 'Ilmv. of Noble Sur- Roast- Agent halogen Ex Carrier metal face ing Halogenating in intro- Tech- No l I mZ/g t "C agent Solvent moles atm. C duced nique 3 Mp Ru-Rh(50/50) 32o 4oo Al 'i. it; a.) 301) et- (3, in Htsu 5.24 l

5 Al 0,, none 220 400 Al (I. (iso bu) 200 cc nC 0.1 He I70 5.'-) l 6 Al. 0., Plan so so 4m 4on1 Al (t tti H t. 2 liters n(: 0.! N. I00 x 2 8 Si Ir 190 500 Al (l H 300 cc 11C... 002 CH 150 L: l

Al. 0.. Pt on 400 Al. (I ((1. H,, M 2 lat-rs (y a! H. I00 ss 3 I2 AI. 0 Pa 41o 400 AI (1 ((1 H, o cc 110 0.l H. loo 5.! 1

( l Proportions are by weight.

volume of 0.6 cc/g. previously roasted for one hour in EXAMPLE l-l air at 400C. After having quickly closed the reactor. vacuum is made therein for one hour by means of a pump. Thereafter. argon is introduced into the reactor.

The temperature being maintained at 50C and the pressure at two absolute bars. we introduce into the reactor 200 cc of a solution containing lmole/liter of ethyl-aluminum dichloride in normal hexane.

After stirring for half an hour at 50C. still under argon atmosphere. the solvent is discharged and the solid is dried.

The resulting product contains about 0.371 by weight of platinum and l l .9/( by weight of chlorine and forms a hydroisomerization catalyst.

EXAMPLE 2 impregnation technique No. 2 (dynamic) In a tubular reactor of stainless steel. we arrange a bed of 100 g of catalyst identical to that used in example l and previously roasted in the same manner.

The reactor is then scavanged by means of a dry hydrogen stream at a rate of 50 liters of hydrogen per liter of catalyst and per hour. at a temperature of 50C and under a pressure of two absolute bars. After that. we introduce, by means of a pump. 1 liter of a solution containing 0.2 mole per liter of Al Cl (C H in normal heptane. at a rate of 500 cc/hour and with a recycling of the reactor effluent.

After 8 hours of circulation. the pump is stopped. the solvent is discharged and the solid dried under hydrogen atmosphere. The analysis carried out on the halogenated solid shows that the latter contains 1 1.771 by weight of chlorine and 0.371 by weight of platinum.

This example shows that the impregnation technique under dynamic conditions leads to the same results as the impregnation technique in static conditions.

EXAMPLES 3 to l3 In this set of examples. we have used both impregnation techniques of examples 1 and 2. In all of these examples. we have used 100 g of a carrier containing 0.35

According to the technique of example 1. we treat g of alumina having a specific surface of 220 m'-/g by means of a solution containing 0.l mole of Al Cl -(C H in 300cc of normal hexane. After l hour of stirring at 100C. we introduce 100 cc of a solution containing 0.5 g of platinum in the form of platinum acetyl acetonate in normal hexane. After stirring for 1 hour at l00C. the solvent is discharged. The reactor is then put under hydrogen atmosphere and heated for 1 hour at 200C under hydrogen atmosphere.

The resulting product contains 0.45 '/r by weight of platinum and 5.7% by weight of chlorine. it has been efficiently used for isomerizing paraffins having 5 and 6 carbon atoms in the -molecule.

EXAMPLE 15 In the tubular reactor of the unit used inexample 2. 50 ccof the catalyst obtained according to example 10 are placed infixed bed. The reactor being maintained under hydrogen circulation at C and 20 absolute bars. we inject normal hexane containing 5.000 ppm by weight of tertiary butyl chloride at a rate of 1 liter per liter of catalyst and per hour. while maintaining a hydrogen flow rate such that the molar ratio H /nC be equal to 3.

The analysis of the liquid outflow from the reactor shows that the latter contains 13% by weight of normal hexane and 87% by weight of isomers of normal hexane.

EXAMPLE 16 In the tubular reactor already used above. we arrange in a fixed bed 50 cc of the catalyst prepared according to example 1 l. The reactor being maintained under hydrogen circulation at 150C and 20 absolute bars. we inject a hydrocarbon charge containing 5071 by weight of normal pentane and 50% by weight of normal hexane to which 1.000 ppm by weight of carbon tetrachloride have been added. The charge is injected at a rate of 2 liters per liter of catalyst and per hour while maintaining 21 hydrogen hourly flow rate such that the molar ratio hydrogen/hydroearbons-be a I The analysis of the reactor outflowshows that the latter has the following composition: I

iso pentane; 25% vby weight normal pentane: 2 5% by weight iso hexanes: 42.5% by weight normal hexane: I 7.57: by weight EXAMPLE 17 In a tubular reactor we place in a fixed bed 100 g of a reforming catalyst containing 0.357: by weight of platinum deposited on an alumina having a specific surface of 220 m'-'/g and a total pore volume of 0.65 cc/g; this catalyst was previously roasted for 1 hour in air at 400C. The reactor is then scavenged by means of a dry hydrogen stream at a rate of 50liters of hydrogen per liter ofcatalyst and per hour at a temperature of 250C and under an absolute pressure of 2 bars. After that, we

8 This example shows that the catalyst used according to the invention has a good initial activity but loses a part of said activity progressively.

The following example shows the effect of the halogenated promoter. I

EXAMPLE 1 8 In the same tubular reactor as previously used, we

' place again 50 cc of the halogenated catalyst prepared Time in hours Charge 3 (w 9 I 50 100 Products .2 by weight Hydrocarbons 0.05 0.95 0,6 0 5 0.4 0.4 0.4 lsopentane 0.4 50. l 5 51.4 50.l 52.5 52.0 52.1 n pentane 99.l 48.40 47.5 48.9 46.6 47.1 47.0 C clopcntane 0.5 0.5 0.5 0.5 0.5 0.5 0.5

Chlorine content at the reactor outlet 95?. 955 960 948 957 959 t l I ('ontent ol'chlorinaled compounds in the charge and in the hydrocarbon effluent from the reactor. cal

culatcd as (linject. by means of a pump, one liter of a solution containing 0.l mole/liter of Al Cl (C- ,H in normal hexane, at a rate of 300 cc/hour, while recycling the reactor effluent and maintaining the temperature at 250C and the hydrogen flow rate at 50 liters per liter of catalyst and per hour. The analysis of the resulting catalyst shows that the latter contains 5.9% by weight of chlorine and 0.32% by weight of platinum.

After having retained in the reactor only 50 cc of said fixed bed catalyst. the temperature and pressure conditions in the reactor are adjusted and maintained at [50C and absolute bars under hydrogen circulation.

Normal pentane having a water content lower than 10 ppm by weight is injected at a rate of 1 liter per liter of catalyst and per hour, while maintaining such a hydrogen flow rate that the molar ratio H /nC,-, be equal to 3.

EXAMPLE 19 In the same tubular reactor as previously used, we place cc of the catalyst prepared according to example 13. y

The reactor being maintained at 140C under hydrogen circulation, under a pressure of 40 absolute bars, we inject normal pentane containing 947 ppm by weight (expressed as chlorine) of ethyl chloride at a rate of 1 liter per liter of catalyst and per hour, while maintaining a such hydrogen flow rate that the molar The reactor effluent, analyzed by gaseous phase ratio H /nC be equal to 4. chromatography, has the composition, expressed ver- The reactor effluent has. versus time, the following sus time. given in the following table: composition:

Time in hours i Charge 3 6 9 I5 30 50 Products 2 by weight Hydrocarbons I 0.05 0.9 0.7 0.5 0.5 0.4 0.5 Isopentanc .0.4 48.2 43.0 32.0 ll 5 10.9 7.9 n pentane 99.l 50.4 55.8 67.0 86.5 88.2 9l.l Cyclopentane 0.5 0.5 0.5 0.5 0.5 0.5 0.5

Time in hours Char e 3 h w IS 50 mo Products J by weight Hydrocarbons C s 0,05 0,9 7 0,4 0.4 0,3 (1,3 Isopentanc 0,4 (\4.5 7 1.3 70. 7h 0 77.0 77.1 n pcntane ).l R-Ll 27.5 22.0 13.1 22.2 22.1 Cyclopentanc 0,5 0.5 0,5 0.5 (1.5 0.5 05 Chlorine content at the reactor 947 9m '05 95s ml won 957 outlet b.w. l

t l Content of chlorinated compounds in the charge and in the h \l.lrocarl\ou effluent from the reactor. calculated as ('l.

The conclusions are the same as in the preceding example.

What we claim as this invention is:

1. In a process for isomerizing a saturated hydrocarbon at 5()-25()C in which said saturated hydrocarbon is contacted with a catalyst containing at least one noble metal from group Vlll of the periodic classification of elements. the improvement comprising carrying out said isomerizing in the presence of a catalyst obtained by contacting a substantially water and molecular oxygen free solid carrier having constitutive-OH groups with a compound of a noble metal from group VIII and with a hydrocarbylaluminum halide.

2. A process according to claim 1, in which the hy drocarbylaluminum halide has the formula Al X Rug in which y is l or 2. X is a halogen and R is a monovalent hydrocarbon radical. and is used in a proportion of l to by weight expressed as halogen with respect to the catalyst. V

3. A process according to claim 1. in which the noble metal is used in a proportion of from 0.05 to 2% by weight with respect to the catalyst.

4. A process according to claim 1 in which the catalyst carrier is alumina.

5. A process according to. claim 1, in which the step of contacting the carrier with the hydrocarbylaluminum halide is carried out at a temperature of from 0 to 250C.

6. A process according to claim 1, in which the carrier is first contacted with the noble metal compound and then treated with hydrogen at 100600C and finally contacted with the hydrocarbylaluminum halide.

7. A process according to claim 1, in which the isomerization is carried out in the presence of hydrogen at a temperature of from 50 to 250C.

8. A process according to claim 1.. in which the isomerization is carried out in the presence of hydrogen at temperature of from to C.

9. A process according to claim 1. in which the isomcrization is carried out in the presence of a halogenated promoter selected from the free halogens. the halohydric acids and the hydrocarbyl halides. used in a proportion of from 10 to 10.000 parts per million of parts i by weight with respect to the hydrocarbon.

10. A process according to claim 9.in which the promoter is recovered after isomerization and subsequently reused in the isomcrization process.

ll. A process according to claim 1 wherein the saturated hydrocarbon has 47 carbon atoms. the isomerization temperature is l00-I50C the carrier is alumina. sufficient hydrocarbylaluminum chloride. expressed as chloride. is incorporated in the alumina to obtain 3-2071 by weight of chlorine to said alumina. the noble metal is incorporated in the catalyst in an amount of 005-271 weight. the isomerization is conducted under a pressure of 5l00 kg/cm at a spatial velocity of 0.2--l0 liters of saturated hydrocarbon per liter of catalyst per hour. and hydrogen is employed in a molar ratio H /hydrocarbon of 1.5 l to 10 1.

12. A process according to claim l l wherein the sat urated hydrocarbons have 5 or 6 carbon atoms.

13. A process according to claim I wherein prior to being contacted with the hydrocarbylaluminum halide. the solid carrier is calcined at a temperature sufficiently high to remove adsorbed water and oxygen but not so high as to remove the constitutive-OH groups.

14. A process according to claim 13 wherein the solid carrier is alumina having a specific surface equal to or UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3 903 195 DATED t September 2, 1975 INVENTOR(S) Jean-Pierre Franck, Et Al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 2 line 2: "the formula A1X R should be -=the formula (3 y) Signed and Sealed this A ttes t:

RUTH C. MASON Arresting Officer C. MARSHALL DANN Commissioner of Parents and Trademarks 

1. IN A PROCESS FOR ISOMERIZING A SATURATED HYDROCARBON AT 50* -250*C IN WHICH SAID SATURATED HYDROCARBON IS CONTACTED WITH A CATALYST CONTAINING AT LEAST ONE NOBLE METAL FROM GROUP V111 OF THE PERIODIC CLASSIFICATION OF ELEMENTS, THE IMPROVEMENT COMPRISING CARRYING OUT SAID ISOMERIZING IN THE PRESENCE OF A CATALYST OBTAINED BY CONTACTING A SUBSTANTIALLY WATER AND MOLECULAR OXYGEN FREE SOLID CARRIER HAVING CONSTITUTIVE-OH GROUPS WITH A COMPOUND OF A NOBLE METAL FROM GROUP VIII AND WITH A HYDROCARBYLALIUMINUM HALIDE.
 2. A process according to claim 1, in which the hydrocarbylaluminum halide has the formula Al XyR(3 4) in which y is 1 or 2, X is a halogen and R is a monovalent hydrocarbon radical, and is used in a proportion of 1 to 20% by weight expressed as halogen with respect to the catalyst.
 3. A process according to claim 1, in which the noble metal is used in a proportion of from 0.05 to 2% by weight with respect to the catalyst.
 4. A process according to claim 1 in which the catalyst carrier is alumina.
 5. A process according to claim 1, in which the step of contacting the carrier with the hydrocarbylaluminum halide is carried out at a temperature of from 0* to 250*C.
 6. A process according to claim 1, in which the carrier is first contacted with the noble metal compound and then treated with hydrogen at 100*-600*C and finally contacted with the hydrocarbylaluminum halide.
 7. A process according to claim 1, in which the isomerization is carried out in the presence of hydrogen at a temperature of from 50* to 250*C.
 8. A process according to claim 1, in which the isomerization is carried out in the presence of hydrogen at a temperature of from 100* to 150*C.
 9. A process according to claim 1, in which the isomerization is carried out in the presence of a halogenated promoter selected from the free halogens, the halohydric acids and the hydrocarbyl halides, used in a proportion of from 10 to 10,000 parts per million of parts by weight with respect to the hydrocarbon.
 10. A process according to claim 9, in which the promoter is recovered after isomerization and subsequently reused in the isomerization process.
 11. A process according to claim 1 wherein the saturated hydrocarbon has 4-7 carbon atoms, the isomerization temperature is 100*-150*C, the carrier is alumina, sufficient hydrocarbylaluminum chloride, expressed as chloride, is incorporated in the alumina to obtain 3-20% by weight of chlorine to said alumina, the noble metal is incorporated in the catalyst in an amount of 0.05-2% weight, the isomerization is conducted under a pressure of 5-100 kg/cm2 at a spatial velocity of 0.2-10 liters of saturated hydrocarbon per liter of catalyst per hour, and hydrogen is employed in a molar ratio H2/hydrocarbon of 1.5 : 1 to 10 :
 1. 12. A process according to claim 11 wherein the saturated hydrocarbons have 5 or 6 carbon atoms.
 13. A process according to claim 1 wherein prior to being contacted with the hydrocarbylaluminum halide, the solid carrier is calcined at a tempErature sufficiently high to remove adsorbed water and oxygen but not so high as to remove the constitutive-OH groups.
 14. A process according to claim 13 wherein the solid carrier is alumina having a specific surface equal to or higher than 5 2/g and the calcination is conducted at 200*-600*C. 